Ring laser gyroscopes (RLGs) and fiber optic gyroscopes (FOGs) have become widely used technologies in many systems to sense the rotation and angular orientation of various objects, such as aerospace vehicles. Both RLGs and FOGs work by directing light in opposite directions around a closed optical path enclosing an area whose normal is along an axis of rotation. If the device is rotated about the axis of rotation, the optical path length for the light traveling in one direction will be reduced, while the optical path length far the light traveling in the opposite direction will be increased. The change in path length causes a phase shiftbetween the two light waves that is proportional to the rate of rotation.
Generally speaking, the signal to noise sensitivity of such gyroscopes increases as the optical path lengths and diameters of the closed path are increased. In this sense, both RLGs and FOGs have an advantage in that light is directed around the axis of rotation multiple times. In RLGs, a series of mirrors is used to repeatedly reflect the light around the axis forming a high finesse resonator. In FOGs, the light travels around the axis through a coil (with numerous turns) of optical fiber, which often has a length of several kilometers.
In recent years, resonator fiber optic gyroscopes (RFOGs) have been developed which combine the above-described path length benefits of RLGs and. FOGs into a single device that uses both a recirculating element, such as a mirror or a fiber coupler, and a multi-turn optical fiber coil to form an optical resonator. The combination of the benefits of RLGs and FOGs allows RFOGs to use shorter optical fiber and to be very small. One difficulty associated with RFOGs is that phase shifts often occur that are not attributable to rotation, but rather errors due to the fact that monochromatic light is propagating in a glass medium provided by a conventional optical fiber. Additionally, besides the mirror and/or coupler and fiber coil, RFOGs typically rely on complicated optical and electronic systems to process and modulate the laser light that is directed into the resonator from an external laser or lasers, as well as process the light signal that comes out of the resonator. These electronic systems, including the external laser(s), can increase the overall size and costs of the RFOGs.
Accordingly, it is desirable to provide a gyroscope system with simplified electronic signal processing systems. In addition, it is desirable to provide a gyroscope system that does not require a separate, external laser source or multiple sources. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.